Ring resonator with integrated photodetector for power monitoring

A photodetector system, comprising:

• a ring resonator device including a built-in photodetector device, the ring resonator device including a passive optical cavity, the built-in photodetector device including a first implant region formed within an inner radial portion of the passive optical cavity, the first implant region having a first type of doping material implanted into the passive optical cavity, the built-in photodetector device including a second implant region formed within the inner radial portion of the passive optical cavity, the second implant region having a second type of doping material implanted into the passive optical cavity, the second type of doping material being different than the first type of doping material, the built-in photodetector device including an intrinsic absorption region present within an outer radial portion of the passive optical cavity between the first implant region and the second implant region, the built-in photodetector device including a first electrical contact electrically connected to the first implant region and a second electrical contact electrically connected to the second implant region;
• and
• a detecting circuit electrically connected to the first electrical contact and the second electrical contact, the detecting circuit configured to apply a reverse-bias voltage to the first and second implant regions to create a charge collection field within the intrinsic absorption region between the first and second implant regions, the detecting circuit configured to detect a photocurrent caused by photoabsorption-generated charge carriers swept into the first and second implant regions by the charge collection field.

A method for detecting optical power within a ring resonator device, comprising:

• having a photodetector device built in to a passive optical cavity of a ring resonator device, the passive optical cavity positioned next to an optical waveguide such that light traveling through the optical waveguide will evanescently couple into the passive optical cavity, the photodetector device including a first implant region formed within an inner radial portion of the passive optical cavity, the first implant region having a first type of doping material implanted into the passive optical cavity, the photodetector device also including a second implant region formed within the inner radial portion of the passive optical cavity, the second implant region having a second type of doping material implanted into the passive optical cavity, the second type of doping material being different than the first type of doping material, the photodetector device also including an intrinsic absorption region present within an outer radial portion of the passive optical cavity between the first implant region and the second implant region, the photodetector device also including a first electrical contact electrically connected to the first implant region and a second electrical contact electrically connected to the second implant region;
• electrically connecting the first electrical contact to a detecting circuit;
• electrically connecting the second electrical contact to the detecting circuit;
• operating the detecting circuit to apply a reverse-bias voltage to the first and second implant regions of the photodetector device to create a charge collection field within the intrinsic absorption region between the first and second implant regions;
• and
• operating the detecting circuit to detect a photocurrent caused by photoabsorption-generated charge carriers swept into the first and second implant regions by the charge collection field.